The acceleration and de-acceleration of electrons on a surface, generates electromagnetic radiation. Large groups of electrons comprise currents on the surface of an antenna. That current creates electromagnetic waves that are radiated into space. The direction of the electric field created by that radiation determines the polarization of the antenna. For example, some antennas have a horizontal electric field during use. Other antennas have a vertical electric field. The plane of this electric field, and the direction of propagation, determines the polarization of the antenna. Most antennas only have one polarization. A dual polarization antenna can respond to both horizontal and vertical polarizations at the same time.